The present invention relates to the field of impedance transformation networks for matching the impedances of antenna networks to associated tuner circuits.
Impedance transformation networks, commonly referred to as Balun networks, are utilized to match the impedances of antennas to associated RF circuitry employed in tuners of television receivers. Traditionally these Balun networks have taken the form of transformer windings which tend to be relatively bulky, difficult to manufacture and expensive. To overcome these deficiencies, Balun networks including a printed circuit board having a strip-like conductor and a ground conductor arranged with respect to each other so as to form a transmission line with the proper characteristics to match the impedances of antenna networks and RF tuner circuitry have been proposed because of their relative compactness, ease of manufacture and cost effectiveness.
Not only is it desirable that a Balun network provide the impedance matching functions set forth above, but it is also desirable that a Balun network include provisions which isolate the receiver from excessively high energies which may be induced by lightning.